1. Field of the Invention
The invention relates to locating wireless mobile devices.
2. Related Art
Using wireless communication, mobile devices can communicate with an application server while continuing to move about. This allows the application server to track locations of those mobile devices, such as for a customer application. Customers might wish to know the location of those mobile devices for a number of possible reasons, such as for example to track actions of the carriers of those mobile devices, and to determine the closest mobile device to a selected location. The frequency with which the application might need to know the location of the mobile device can vary substantially with the desires of the customer and with the selected mobile device.
A first set of known systems include devices (herein sometimes called “set-top boxes”) that are coupled to a mobile device, such as a vehicle, and automatically report the location of the vehicle to a server, in response to requests by the server from time to time. These requests are sometimes called “ping” messages. The set-top boxes respond to the ping message by generating a PVT (position, velocity, and time) message, and sending that message back to the server using a cellular modem. While these systems generally achieve the goal of determining where the vehicle is from time to time, they are subject to several drawbacks. First, there is no way of knowing, regardless of the response to the ping message, whether or not the vehicle and its personnel (such as the driver and any ancillary personnel assigned to that vehicle) are anywhere near the vehicle, or what they are doing, or whether they intend to return to the vehicle at any particular time. Second, it may sometimes occur that the vehicle personnel might not wish to respond to the ping message (such as for example if they are on a lunch break), but they do not have any way to cause the set-top box to refuse to respond to the ping message.
A second set of known systems include GPS-enabled mobile phones, which include both a mobile phone and its associated software, as well as a GPS antenna and associated software for GPS tracking. In one known system, GPS-enabled mobile phones have been equipped to respond to a ping message. While this system generally achieves the goal of determining where the mobile phone user is from time to time, it is subject to several drawbacks. If the mobile phone user does not wish to be tracked, that user is capable of turning the mobile phone off, which would prevent both reception and response to a ping message. Alternatively, if the mobile phone user does not wish to be tracked, the mobile phone user is capable of turning off the GPS tracking application, which would prevent a response to a ping message. Third, if the user does either of these in an effort to prevent being tracked, it can take substantial time (as much as up to 10-15 minutes) for the GPS tracking application to re-determine the location of the GPS-enabled mobile phone. This latter effect is herein sometimes referred to as a “cold start” of the GPS tracking application.
Accordingly, it would be advantageous to provide techniques capable of allowing users more flexibility to determine whether they are tracked, without drawbacks of the known art.